import java.util.HashSet;

public class demo7 {
    public boolean containsNearbyDuplicate(int[] nums, int k) {
        HashSet<Integer>set=new HashSet<Integer>();
        for(int i=0;i<nums.length;i++) {
            if(set.contains(nums[i]))return true;
            else {
                set.add(nums[i]);
            }
            if(set.size()>k) {
                set.remove(nums[i-k]);
            }
        }
        return false;
    }
}
